A structural investigation of heteroleptic lanthanide substituted cyclopentadienyl complexes

The substituted cyclopentadienyl group 1 transfer agents KCp '', KCp''' and KCptt (Cp '' = {C5H3(SiMe3)(2)-1,3}(-); Cp''' = {C5H2(SiMe3)(3)-1,2,4}(-); Cp-tt = {C5H3(Bu-t)(2)-1,3}(-)) were prepared by modification of established procedures and the structure of [K(Cp '')(THF)](infinity). THF (1) was obtained. KCp '' and KCp '' were reacted variously with [Ln(I)(3)(THF)(4)] (Ln = La, Ce) in 2 : 1 stoichiometries to afford monomeric [La(Cp '')(2)(I)(THF)] (2a.THF) and the dimeric complexes [La(Cp '')(2)(mu-l)](2) (2a), [Ce(Cp '')2(mu-I)](2) (2b) and [Ce(Cp-tt)(2)(mu-I)](2) (3). KCp''' was reacted with [Ce(I)(3)(THF)(4)] to afford the mono-ring complex [Ce(Cp''')(I)(2)(THF)(2)] (4), regardless of the stoichiometric ratio of the reagents. Complex 4 was reacted with [KN(SiMe3)(2)] to yield [Ce(Cp''')(2)(I)(THF)] (5), [Ce(Cp'''){N(SiMe3)(2)}(2)] (6) and [Ce{N(SiMe3)(2)}(3)] by ligand scrambling. Complexes 1-6 have all been structurally authenticated and are variously characterised by other physical methods.